Page 1 - 3. LESSON NOTES-EFFECT OF PRESSURE ON STATES OF MATTER

SAI International School
Class-IX

Subject-Chemistry
Topic-Matter in our surroundings
Sub topic- Effect of pressure on states of matter

LESSON NOTES
Change of state of matter due to effect of pressure
Pressure creates no effect on solids or liquids because both these states of matter
are non-compressible. But if pressure is increased on solid it breaks.

But on the other hand application of pressure with reduced temperature can liquefy
gases. For instance, during parties or stage shows you must have noticed smoke
that spreads all around the stage. It is nothing but dry ice (solid carbon-dioxide).
Solid carbon-dioxide is stored under high pressure that vapourises instantly as soon
as the pressure is reduced to 1 atmospheric pressure.

• Gas to liquid: Gases can be liquefied by applying pressure and reducing the
temperature. When a high pressure is applied to a gas, it gets compressed and if the
temperature is lowered, the gas is liquefied.
• Solid CO2 gets converted directly to gaseous state on decrease of pressure to 1
atmosphere without coming into liquid state. This is the reason that solid carbon
dioxide is also known as dry ice.

Fig. Application of pressure can convert gas to liquid which in turn can convert the
liquid to solid due to compression of particles.

Activity to show that gases are highly compressible as compared to solids and
liquids.
Take three 100 ml syringes and remove their pistons. Also, close the nozzles of the
syringes with rubber
corks. Then, fill one syringe with chalk powder and the other with water. Now, insert
the pistons back into the syringes and push them.

1